It is a common for machine tools of various types to include a cover member disposed over at least the machining portions of the tool to confine coolant and workpiece shavings, cutting chips and the like. In conventional arrangements, the cover unit is disposed over the machine tool and is provided with one or more openings for facilitating maintenance of the machine tool and interchange of workpieces and tools used therein.
An example of an enclosure for a machine tool having an automatic tool changer is shown in U.S. Pat. No. 3,355,799, which issued to J. Daugherty. Particularly, the Daugherty enclosure was contemplated as a unitized and free standing cabinet which completely enclosed the storage matrix, linear transfer mechanism and rotary arm in order to protect these parts from ambient dust and dirt. The Daugherty enclosure includes a matrix cabinet and a linear transfer mechanism housing, wherein the matrix cabinet has an L-shaped door providing a corner access opening for loading selected tools. The housing also includes a closure member covering its front portions adapted to be automatically opened and closed in timed relation with the tool change cycle, thereby permitting exchange of a tool from the tool changer enclosure. A hydraulic cylinder moves the door along a track in order to open the housing to provide clearance for the tool transfer arm during tool change procedures. All of the openings are provided with seals to enable pressurization of the enclosure to prevent dust and other debris from entering into and accumulating upon the tool changing apparatus.
Another machine tool with a guard/cover apparatus is shown in U.S. Pat. No. 3,930,302, which issued to Y. Ochiai, et al. The Ochiai, et al. machine tool is contemplated as including an automatic tool changer with radially arranged tools provided above the spindle. A pair of guard covers are situated between the spindle head and tool storage magazine, and a hydraulic actuator is provided to open the guard covers to permit tool exchange, and to close the covers for machining operations. A separate guard cover is fixed on a column over the entire circumference of the tool magazine, except at the tool change position where the pivotal guard covers are arranged.
Another cover unit for a machine tool is shown in U.S. Pat. No. 4,999,895, which issued to A. Hirose, et al. The Hirose, et al. cover unit is provided for a multi-work station machine tool and includes a pair of doors each adapted to close half of an opening formed in the front panel of the cover unit. The doors are connected to hydraulic cylinders and are alternately opened to enable exchange of workpiece pallets on a stationary machining table. This arrangement is aimed at enabling exchange of a workpiece at a second position while machining is taking place at a first position. The individual doors enable better confinement of cutting chips and coolant by minimizing the area of the cover which must be opened to the exterior during actual machining procedures. Larger doors are also provided adjacent the smaller doors to enable maintenance access to the machine tool.
Clearly, a number of machine tool cover arrangements have been available in the industry, in modern machine tool applications, however, relatively free interchange of tools and workpieces must often be accommodated, and machining centers are preferably reconfigurable between milling, turning, and other machining operations. While the enclosure must effectively isolate the machining area from the external environment and from the other structural parts of the machine, it must also provide access for maintenance and repair of the machine tool. Moreover, the cover structure must preferably be able to accommodate various configurations of the machine tool with minimal substantive changes to the cover structure itself.
Heretofore, there has not been available a machine tool covering assembly or structure which provided complete shielding of every structural part of the machine from the working environment, as well as effective isolation of the working environment from the external environment, while easily accommodating the interchange of workpiece members and tools. In applications where covering doors or openings were provided, the machine had to be idle (i.e., in a non-machining mode) while such doors were opened and/or closed. Additionally, with the increasing use and need for reconfigurable machine tools, a cover assembly which can efficiently accommodate a variety of different machine tool application configurations with minimal structural changes in the cover assembly itself, and which permits relatively convenient access to the machine tool for maintenance, tool exchange, and workpiece exchange is needed in the industry.